1. Field of the Invention
The present invention relates to optical fibers, in particular cleaving of optical fibers to shorten their length and produce a flat end on the fiber.
2. Description of Related Art
There are many advantages to transmitting light energy via optical fiber waveguides and the use thereof is diverse. Single or multiple fiber waveguides may be used simply for transmitting visible light to a remote location. Complex communication systems may transmit multiple specific optical signals. These devices often require the coupling of fibers in end-to-end relationship with the coupling representing a source of light loss. The cleaved end should be smooth and defect-free. If the ends of the fiber are uneven, excessive light loss can result due to reflection and refraction of light at the cleaved end surface (e.g., a splice or juncture region). For the vast majority of fiber optic applications, it is important to cleave the fiber such that the end of the fiber is completely flat in preparation for coupling. When placing optical fibers in end-to-end relationship, to minimize light loss, it is desirable to have the end faces of the fibers be smooth and lie in a plane perpendicular, or at a specific angle, to the axis of the fibers. In short, the cleaved fiber end face needs to be a single plane that is mirror quality to optimize coupling between fibers in demountable connectors, permanent splices and photonic devices.
Conventional cleaving is done by either use of mechanical cleaving or laser cleaving. Heretofore, according to one conventional mechanical cleaving approach to produce a cleave, the optical fiber is first placed under axial tension, and then the optical fiber is scored to initiate the cleave. The resulting cleave angle and surface features are a direct result of both the quality of the score and axial stress and/or strain distribution in the optical fiber. The axial tension applied is necessary to propagate the cleave. However, too much tension will cause the cleave to propagate too fast, creating hackle on the cleaved end. If too little tension is used, the scoring edge will be required to penetrate too deeply into the fiber to initiate the cleave, giving a poor cleave.
Given the imperfections created at the cleaved ends of the fibers, current cleaving approaches involve conventional cleaving of the optical fiber followed by mechanical polishing of the resultant end face to eliminate imperfections of the cleaved face non-planar form. An alternate approach is to use the above process but with mechanical polishing replaced by laser polishing. Such polishing step can be automated, but it requires elaborate and expensive equipment and a rather complex procedure, which limit the operation to being performed in a factory or laboratory. Furthermore, the shape of the fiber is distorted, often increasing in diameter, when the end of the fiber melts and resolidifies as a result of the laser polishing process.
Laser cleaving may produce either an end fiber surface that still requires further polishing to produce a flat cleaved surface, or an end surface that has been laser polished during the laser cleaving process. Laser cleaving produces a significantly better optical surface at the cleaved ends of fibers, but the process must be carried out using dedicated cleaving equipments (see, e.g., automated and fully integrated laser cleaving systems distributed by OpTek Systems; www.opteksystems.com).
The relatively widespread and ever increasing utilization of optical fibers in communication systems, data processing and other signal transmission systems has created a demand for satisfactory and efficient means of inter-joining terminals. Currently most demountable fiber connectors are factory installed. For field installation of optical fibers, it is particularly desirable to develop a process that can be simply and reliably deployed to properly cleave the optical fibers so as to minimize light loss when the fibers are subsequently coupled. There is a need to develop an effective, efficient and reliable approach to prepare optical fiber end faces.